Method for improved deposition of dielectric material

ABSTRACT

A gas delivery device useful in material deposition processes executed during semiconductor device fabrication in a reaction chamber, including the gas delivery device of the present invention and a method for carrying out a material deposition process, including introducing process gas into a reaction chamber using the gas delivery device of the present invention. In each embodiment, the gas delivery device of the present invention includes a plurality of active diffusers and a plurality of gas delivery nozzles, which extend into the reaction chamber. Before entering the reaction chamber through one of the plurality of gas delivery nozzles, process gas must first pass through one of the plurality active diffusers. Each of the active diffusers is centrally controllable such that the rate at which process gas flows through each active diffuser is exactly controlled at all times throughout a given deposition process.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 09/649,897,filed Aug. 28, 2000, now U.S. Pat. No. 6,896,737, issued May 24, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to reaction chambers used for thedeposition of material layers during fabrication of semiconductordevices. Specifically, the present invention relates to an improved gasdelivery device for improved control of chemical vapor delivery within asemiconductor device fabrication chamber.

2. State of the Art

As is well known, processes for semiconductor device fabricationgenerally involve the deposition and processing of one or more materiallayers on a semiconductor substrate. Often, these different materiallayers are formed using well-known chemical vapor deposition (CVD)processes, such as thermally enhanced (TE) CVD, plasma enhanced (PE) CVDor high density plasma (HDP) CVD. Such techniques require placing asemiconductor substrate within a sealed reaction chamber and introducingone or more chemical vapors into the sealed reaction chamber underconditions known to result in the deposition of a desired material.However, in order to ensure the deposition of high-quality materiallayers using known deposition techniques, the quantity and quality ofthe gaseous chemicals entering the sealed reaction chamber must becarefully controlled throughout the deposition process. Failure tocontrol the amount of chemical vapor entering a reaction chamber, thedistribution of chemical vapor within the reaction chamber, or the rateat which a given amount of chemical vapor enters the reaction chambercan each result in low-quality material layers that substantiallycompromise the quality of the subsequently completed semiconductordevice.

For example, HDP CVD processes are often used to fill various features,such as isolation gaps or trenches, included in an intermediatesemiconductor device structure with a dielectric material, such assilicon dioxide (SiO₂). HDP CVD processes are currently favored forfilling isolation gaps or trenches because the simultaneous dielectricdeposition and sputter etch produced by such processes allows small,high-aspect ratio features to be reliably filled with dielectricmaterial. However, imprecise control of the reactant gases used for HDPdeposition will either result in damage to underlying device features ordeposition of a low-quality dielectric layer, either of whichsignificantly reduces the performance and reliability of subsequentlycompleted semiconductor devices.

Presently used HDP CVD processes often utilize a gas mixture containingoxygen (O₂), silane (SiH₄), and inert gases, such as argon (Ar), incombination with plasma generation and application of an RF bias to thetarget substrate, to achieve simultaneous dielectric deposition andsputter etching. The interaction of SiH₄ and O₂ molecules in the HDPenvironment results in the deposition of silicon dioxide (SiO₂) over thesemiconductor substrate. However, as SiO₂ is deposited over thesemiconductor substrate, molecules of the inert gas included in the gasmixture are ionized by the plasma produced within the chamber. Due tothe RF bias applied to the semiconductor substrate, the ionizedmolecules accelerate toward and impinge upon the surface of thesubstrate. As a result, SiO₂ is simultaneously deposited on the wafersurface and sputter etched by accelerated ionized particles. In most HDPCVD processes, the ratio of deposition rate to etch rate ranges fromabout 2% to about 20%. It is the simultaneous deposition and sputteretch created by HDP CVD processes that allow higher aspect ratiofeatures to be filled with the desired dielectric material.

In order to better describe the simultaneous deposition and sputter etchof a typical HDP CVD process, drawing FIG. 1 through 4 schematicallyillustrate various stages of such a process. Illustrated in drawing FIG.1 is an intermediate semiconductor device 5 including a semiconductorsubstrate 10 with an isolation gap 12 disposed between two circuitelements 14. As can be seen in drawing FIG. 1, due to the interaction ofSiH₄ with O₂ during a typical HDP CVD process, a layer of SiO₂ 16 beginsto form over the two circuit elements 14 and within the isolation gap12. As the SiO₂ 16 is deposited, however, charged ions (not shown indrawing FIG. 1) impinge on and sputter etch the newly deposited layer ofSiO₂ 16. Because the sputter etch rate created by the impinging ions isapproximately three to four times higher at 45E than it is at 90E,facets 20 form at the corners of the two circuit elements 14 during thedeposition process. Illustrated in drawing FIGS. 2 through 4 is thecontinuing growth of the layer of SiO₂ 16 and filling of the isolationgap 12 as would be expected from an HDP process having an optimizeddeposition-to-etch ratio.

However, as is well known, the deposition-to-etch ratio can becontrolled by varying the rate of flow of SiH₄ or other process gasesinto the reaction chamber. For example, if the flow rate of SiH₄ isincreased, the deposition rate of the HDP CVD process will increase. Asshown in drawing FIG. 5, if the deposition-to-etch ratio is increasedabove the optimum, the facets 20 begin moving away from the corners ofthe two circuit elements 14, and cusps 22 begin to form on sidewalls 24of the isolation gap 12. Cusp formation is believed to result fromredeposition of etched SiO₂ on opposing surfaces through line-of-sightredeposition. Significantly, the rate of redeposition increases as thedistance (represented by the letter “D”) between opposing facets 20decreases. As the facets 20 move away from the corners of the twocircuit elements 14, the line-of-sight paths are shortened and sidewall24 redeposition is increased. Eventually, the cusps 22 meet, preventingfurther deposition below the cusps 22 and creating a void 25 in thedielectric material layer SiO₂ 16 deposited within the isolation gap 12,as can be seen in drawing FIG. 6.

Additionally, if the rate at which inert gas (e.g., Ar) is introducedinto an HDP CVD chamber is increased or flow of SiH₄ is decreased, thesputter etch rate of the HDP CVD process will increase, therebydecreasing the deposition-to-etch ratio. As shown in drawing FIG. 7,decreasing the deposition-to-etch ratio can result in the etching or“clipping” of material from the corners 23 of the two circuit elements14. Clipping progressively damages the circuit elements as the HDP CVDprocess progresses and will potentially compromise the performance ofthe two circuit elements 14 or render the two circuit elements 14completely inoperable.

As is easily appreciated from the foregoing, the flow rate of reactantgases used to effect HDP CVD processes, particularly those gases thataffect the deposition-to-etch ratio, must be precisely controlled. Thisis especially true as the device features to be filled by HDP CVDprocesses shrink well below 0.5 μm. However, known gas delivery systemsused in conjunction with HDP CVD reactors do not provide the range ofcontrol necessary to consistently deposit high quality dielectricmaterial within the ever-shrinking, high-aspect-ratio device featuresincluded in state of the art semiconductor devices.

A typical gas distribution device 28 used for gas delivery within an HDPCVD reaction chamber is illustrated in drawing FIG. 8. Such a gasdistribution device 28 includes a single mass flow control valve (“MFC”)30, a gas inlet 32, a manifold ring 34, and a plurality of nozzles 36a-36 h. Often during an initial period of a “gas-on” phase of an HDP CVDprocess, a build up of process gas pressure occurs within the gasdelivery system, and where a gas distribution device 28 such as thedevice illustrated in drawing FIG. 8 is used, the initial build up ofprocess gas pressure results in a high initial flow of reactant gasthrough the nozzles located closest to the gas inlet 32. However, whilethis high flow is occurring at the nozzles 36 a, 36 h closest to the gasinlet 32, very little, if any, reactant gas flows through those nozzles36 d, 36 e located farthest away from the gas inlet 32 for approximatelyone to two seconds. Thus, deposition of SiO₂ on the target substrate(not shown) begins in the area of the substrate underlying those nozzles36 a, 36 h closest to the gas inlet 32 before any deposition has takenplace in the area of the target substrate underlying those nozzles 36 d,36 e located farthest from the gas inlet 32. Moreover, the initial buildup of process gas pressure causes process gas to flow through thosenozzles 36 a, 36 h closest to the gas inlet 32 at an undesirably highrate, and the deposition-to-etch ratio of the HDP CVD process moves awayfrom the desired optimum, until the pressure of the process gas withinthe gas distribution device 28 stabilizes.

Where a gas delivery ring such as the one illustrated in drawing FIG. 8is used to deliver SiH₄ during an HDP CVD process, the quality of theresulting dielectric material may, therefore, be severely compromised.During the initial period of an SiH₄ gas-on phase, the high flow of SiH₄through the nozzles 36 a, 36 h located closest to the gas inlet 32 ofthe gas distribution device 28 will cause the deposition-to-etch ratioto increase away from the desired optimum. Even though thisinconsistency may last as little as one second, the deposition-to-etchratio is effected long enough to affect deposition of at least theinitial nuclear layer of the deposited dielectric material in such a wayas to cause voids or other material inconsistencies within the depositeddielectric layer as the deposition process continues. Thus, theinconsistent gas flow provided by known gas delivery rings often rendersentire wafers or portions of wafers unusable.

As can be easily appreciated, there is a need in the art for a gasdelivery apparatus that allows reliable, precise control of gas flow atall times during a material deposition process. Such a device would notonly be desirable because it would eliminate the problems caused by theinconsistent delivery of process gases associated with known devices,but such a device will likely prove necessary as the dimensions of stateof the art semiconductor devices continue to shrink.

BRIEF SUMMARY OF THE INVENTION

The gas delivery device of the present invention addresses the foregoingneeds by enabling precise control of process gas flow into a reactionchamber. In each embodiment, the gas delivery device of the presentinvention includes a plurality of active diffusers and a plurality ofgas delivery nozzles which extend into the reaction chamber. Beforeentering the reaction chamber through one of the plurality of gasdelivery nozzles, process gas must first pass through one of theplurality of active diffusers. Each of the active diffusers is centrallycontrollable such that the rate at which process gas flows through eachactive diffuser is exactly controlled at all times throughout a givendeposition process. As a result, the gas delivery device of the presentinvention not only eliminates any undesirable increase in the rate ofprocess gas flow during the initial period of a “gas on” phase of amaterial deposition process, but enables exact control of thedeposition-to-etch ratio of any HDP CVD process. Further, each of theplurality of active diffusers included in the gas delivery device of thepresent invention is specifically positioned to minimize anyinconsistencies in the time needed for the process gas to flow from theplurality of active diffusers and through each nozzle of the pluralityof gas delivery nozzles. Thus, the gas delivery device of the presentinvention prevents the formation of material voids associated with theinconsistent flow rates of process gas during material depositionprocesses, such as an HDP CVD process, while reducing or eliminating anyproblems associated with non-uniform distribution of process gas withina reaction chamber.

The present invention also includes a reaction chamber for use inmaterial deposition processes. The reaction chamber includes a sealablechamber and a gas delivery device. The reaction chamber may furtherinclude various other known features necessary for carrying out adesired material deposition process. Significantly, because the reactionchamber incorporates the gas delivery device, the reaction chamberenables precise control of process gas dosing within the reactionchamber throughout any given material deposition process.

Furthermore, the present invention includes a method of carrying out amaterial deposition process. The method of the present inventionincludes providing a reaction chamber, providing a gas delivery deviceaccording to any one of the embodiments of the gas delivery device ofthe present invention, disposing a semiconductor substrate within thereaction chamber, and introducing a desired process gas into thereaction chamber using the gas delivery device of the present invention.

Various other aspects and advantages of the present invention willbecome apparent to those of skill in the art through consideration ofthe ensuing description, the accompanying drawings, and the appendedclaims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The figures presented in conjunction with this description are notactual views of any particular portion of a device or component, but aremerely representations employed to more clearly and fully depict thepresent invention.

FIG. 1 through 4 illustrate deposition of a dielectric material over anintermediate semiconductor device during a desirable HDP CVD process;

FIG. 5 and FIG. 6 illustrate the formation of a material void within adielectric material deposited over an intermediate semiconductor devicethat may occur when the deposition-to-etch ratio of an HDP CVD processis increased away from an optimum value;

FIG. 7 illustrates the clipping of device features that may occur whenthe deposition-to-etch ratio of an HDP CVD process is decreased awayfrom an optimum value;

FIG. 8 schematically illustrates a gas delivery device currently used todeliver process gas within a reaction chamber used for HDP CVD;

FIG. 9 schematically illustrates the first embodiment of a gas deliverydevice of the present invention;

FIG. 10 and FIG. 11 schematically illustrate alternative configurationsof an active diffuser that may be used in each of the embodiments of thegas delivery device of the present invention;

FIG. 12 through 16 schematically illustrate further embodiments of thegas delivery device of the present invention; and

FIG. 17 provides a schematic illustration of a reaction chamber of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the gas delivery device 50 of the presentinvention is illustrated in drawing FIG. 9. The gas delivery device 50of the first embodiment includes a plurality of gas delivery nozzles 36a–36 h extending through the reaction chamber wall 118, a manifold 54including gas inlets 56 a, 56 b, and active diffusers 58 a, 58 b.Process gas is delivered to each of the active diffusers 58 a, 58 bthrough a branched gas delivery line 60. As the process gas passesthrough the active diffusers 58 a, 58 b, it enters the manifold 54through the gas inlets 56 a, 56 b. From the manifold 54, the process gasis delivered into a reaction chamber (not illustrated in drawing FIG. 9)through the plurality of gas delivery nozzles 36 a-36 h. As can also beseen in drawing FIG. 9, the active diffusers 58 a, 58 b are positionedrelative to the manifold 54 and associated gas delivery nozzles 36 a-36h such that inconsistencies in the time needed for process gas to flowfrom the active diffusers 58 a, 58 b and through each of the gasdelivery nozzles 36 a-36 h are minimized or eliminated. Furthermore, inorder to facilitate production and maintenance of a consistent processgas pressure within the manifold 54, the gas delivery device 50according to the first embodiment may include one or more manifoldpartitions 61 a, 61 b within the manifold 54.

The operation of each of the active diffusers 58 a, 58 b is controlledby a central controller 62, which may include, for example, aprogrammable computer circuit. The central controller 62 is placed incommunication with each of the active diffusers 58 a, 58 b using one ormore suitable communication lines 57 a, 57 b, such as well-knownelectrical or optical communication lines. The central controller 62 iscapable of continuously monitoring the process gas pressure within ornear each of the active diffusers 58 a, 58 b using information providedby a pressure sensor (not illustrated in drawing FIG. 9) placed withinor near each active diffuser 58 a, 58 b. Generally, the active diffusers58 a, 58 b are controlled to prevent gas flow from the branched gasdelivery line 60 and into the manifold 54 until a desired minimumprocess gas pressure is achieved within or near each active diffuser 58a, 58 b. Once the desired minimum process gas pressure is achievedwithin or near each active diffuser 58 a, 58 b, however, the centralcontroller 62 instructs the active diffusers 58 a, 58 b viacommunication lines 57 a, 57 b to operate such that a desired rate ofprocess gas flow into the associated reaction chamber is exactlyprovided by each active diffuser 58 a, 58 b.

Because the central controller 62 is capable of continuously monitoringthe process gas pressure within or near each one of the active diffusers58 a, 58 b, the operation of each of the active diffusers 58 a, 58 b maybe continually and independently adjusted to compensate forinconsistencies in process gas pressure within the branched gas deliveryline 60, regardless of whether such inconsistencies are expected, as inthe case of a pressure build up during the initial period of a gas-onphase, or unexpected, as may occur due to malfunction or fouling of oneor more components of the gas delivery device 50. Moreover, usingcontinuously updated pressure information, the central controller 62 cancontrol each active diffuser 58 a, 58 b such that a desired process gasflow is precisely achieved through each active diffuser 58 a, 58 b, evenif different process gas pressures are consistently created at thedifferent active diffusers 58 a, 58 b.

Illustrated in drawing FIG. 10 is an active diffuser 58 suitable for usein any one of the embodiments of the gas delivery device of the presentinvention. As is illustrated in drawing FIG. 10, each active diffuser 58includes a body 70 having an inlet 72 and an outlet 74, a modulator 78,and a transducer body 80, which prevents gas flow through the outlet 74when in a closed state, but allows gas flow through the outlet 74 whenin an open state. In addition, each active diffuser 58 may optionallyincorporate one or more particulate filters 77 or a pressure sensor 76.The pressure sensor 76, which may include any suitable pressure sensingtechnology, such as a known pressure transducer, continuously producessignals indicative of the process gas pressure within the activediffuser 58. Such signals are preferably digital signals and arereadable by a central controller 62. The central controller 62 mayinclude, for example, a programmable computer circuit (not illustratedin FIG. 10). The signals produced by the pressure sensor 76 arecommunicated to the central controller 62 via one or more suitablecommunication lines 57, such as well-known electrical or opticalcommunication lines. Using the signals continuously produced by thepressure sensor 76, the central controller 62 directs the modulator 78to act upon the transducer body 80 such that the transducer body 80alternates between closed and open states at a rate that will produce adesired dosage of process gas in the context of the sensed process gaspressure. The central controller 62 is placed in communication with themodulator 78 of the active diffuser 58 and controls the modulator 78 viaone or more other suitable communication lines 57 known in the art, suchas known electrical or optical communication lines.

However, as is illustrated in drawing FIG. 11, an active diffuser 58suitable for use in the various embodiments of the gas delivery deviceof the present invention need not incorporate a pressure sensor 76. Forexample, a known pressure sensor 76 may extend through a branched gasdelivery line 60 near the inlet 72 of the active diffuser 58. In such anembodiment, the pressure of the process gas within the active diffuser58 would be accurately estimated, and the function and operation of thecentral controller 62, the pressure sensor 76, and the active diffuser58 remain substantially the same. That is, the pressure sensor 76continuously produces signals indicative of the process gas pressurewithin the branched gas delivery line 60 near the inlet 72 of the activediffuser 58. Alternatively, a pressure sensor 76 may extend through agas outlet line 75 near the outlet 74 of the active diffuser 58. Thepressure sensor 76 placed near the outlet 74 would sense the pressureproduced by the process gas exiting the active diffuser 58 andcontinuously produces signals indicative of the process gas pressurewithin the gas outlet line 75 near the outlet 74 of the active diffuser58. If desired, pressure sensors 76 may be provided near the inlet 72 ofthe active diffuser 58 and a pressure sensor 76 may be provided near theoutlet 74 of the active diffuser 58. Regardless of the location of thepressure sensors 76, however, the signals produced by the pressuresensors 76 are communicated to and read by the central controller 62,and using the signals continuously produced by the pressure sensors 76,the central controller 62 directs the operation of the active diffuser58 to produce a desired dosage of process gas in light of the sensedprocess gas pressures.

In each of the embodiments of the gas delivery device of the presentinvention, at least one pressure sensor is associated with each activediffuser, as is illustrated in drawing FIG. 10 and drawing FIG. 11.Further, each pressure sensor included in each embodiment of the gasdelivery device of the present invention is placed in communication witha central controller, as illustrated in drawing FIG. 10 and drawing FIG.11. Placing at least one pressure sensor near or within each activediffuser enables accurate sensing of process gas pressure near or withineach active diffuser, thereby enabling more precise control of eachactive diffuser and more accurate dosing of process gas within areaction chamber.

Though any suitable active diffuser may be used in conjunction with thevarious embodiments of the gas delivery device of the present invention,piezoelectric gas valves are presently preferred. The transducer body ofpiezoelectric gas valves includes a piezoelectric element that respondsto voltages applied by an electromagnetic modulator with precisemovements that are directly proportional to the voltage applied. Thus,depending on the voltage applied, the piezoelectric member may be bentto varying degrees, resulting in varying “open” states of thepiezoelectric valve. Moreover, the time required for the piezoelectricelement to respond to an applied voltage is generally less than 2milliseconds. As a consequence, a piezoelectric element may be cycledbetween closed and varying open states hundreds of times each second.These performance characteristics result in a valve that is not onlyeasily and precisely controllable by a central controller, but which isalso capable of consistently providing an extremely wide range ofdesired process gas flows even where the process gas supplied to suchvalves is provided at inconsistent or varying pressures.

Piezoelectric valves and central controllers suitable for use in thevarious embodiments of the gas delivery device of the present inventionmust provide fast response times as well as reliable operation overtime, and such devices are known in the art. For example, EngineeringMeasurements Company (“EMCO”) produces piezoelectric valves andassociated control systems that provide desirable response times andlong-term reliability. The piezoelectric valves and control systemsproduced by EMCO may be used as the active diffusers and centralcontroller associated with each embodiment of the gas delivery device ofthe present invention.

A second embodiment of the gas delivery device of the present inventionis illustrated in drawing FIG. 12. Like the first embodiment illustratedin drawing FIG. 9, the second embodiment of the gas delivery device 100of the present invention includes a plurality of gas delivery nozzles 36a-36 f which extend through the reaction chamber wall 118, a manifold 54having a plurality of gas inlets 56 a-56 f, and a plurality of activediffusers 58 a-58 f, which are placed in communication with a centralcontroller 62 using known communication lines 57 a-57 f, such as knownelectrical or optical communication lines. As is true of the activediffusers 58 a and 58 b depicted in the first embodiment, the activediffusers 58 a-58 f of the second embodiment are controlled viacommunication lines 57 a-57 f by a central controller 62, which mayinclude, for example, a programmable computer circuit. Moreover, the gasdelivery device according to the second embodiment may include one ormore manifold partitions 61 a, 61 b that facilitate production andmaintenance of a consistent process gas pressure within the manifold 54.However, the gas delivery device 100 according to the second embodimentincludes active diffusers 58 a-58 f and gas inlets 56 a-56 fcorresponding to each gas delivery nozzle 36 a-36 f. Such a designsubstantially eliminates any inconsistencies in the time required forprocess gas to travel from the active diffusers 58 a-58 f and througheach of the gas delivery nozzles 36 a-36 f, further assuring consistentdelivery of process gas into the reaction chamber throughout adeposition process.

Additionally, the gas delivery device 100 of the second embodimentincludes a primary gas delivery line 104, a plenum 106, and secondarygas delivery lines 108 a–108 f, each servicing one of the plurality ofactive diffusers 58 a–58 f. Preferably, each of the secondary gasdelivery lines 108 a–108 f is exactly the same length, thereby creatinga process gas distribution system wherein the process gas travelsexactly the same distance before arriving at each of the activediffusers 58 a–58 f. Where the process gas delivered to each of theactive diffusers must travel exactly the same distance, equilibration ofprocess gas pressure at each of the active diffusers becomes lessdifficult.

Of course, each of the embodiments already described may be modified inharmony with the present invention. For example, a gas delivery deviceof the present invention may include any desirable number of primary andsecondary gas delivery lines, plenums, active diffusers, communicationlines, gas inlets, and gas delivery nozzles, or the gas delivery deviceof the present invention may include more than one manifold.

Illustrated in FIG. 13 is a third embodiment of the gas delivery device110 of the present invention, which includes a plurality of activediffusers 58 a-58 d controlled by a central controller 62 via suitablecommunication lines 57 a-57 d, such as known electrical or opticalcommunication lines, as well as a first manifold 54, a plurality of gasdelivery nozzles 36 a-36 h, which extend through a reaction chamber wall118 and are associated with a second manifold 55, and a plurality of gaspassageways 53 a-53 d associated with the first and second manifolds 54,55, respectively. The gas delivery device 110 illustrated in drawingFIG. 13 helps ensure that the process gas leaving each of the activediffusers 58 a-58 d arrives at and passes through each of the gasdelivery nozzles 36 a-36 h at the same time and under the same pressure,particularly where the ratio of active diffusers 58 a-58 d to gasdelivery nozzles 36 a-36 h included in a gas delivery device of thepresent invention, is less than one.

Alternatively, the gas delivery device of the present invention need notinclude a manifold at all. In a fourth embodiment of the gas deliverydevice 112 of the present invention (illustrated in drawing FIG. 14),the gas delivery device 112 includes a primary gas delivery line 104, aplenum 106, and secondary gas delivery lines 108 a–108 d , eachservicing one of a plurality of active diffusers 58 a–58 d , with eachof the active diffusers 58 a–58 d being placed in communication with andcontrolled by a central controller 62 via suitable communication lines57 a–57 d, such as known electrical or optical communication lines. Thegas delivery device 112 according to the fourth embodiment also includesa plurality of tertiary gas lines 114 a–114 h extending between theactive diffusers 58 a–58 d and a plurality of gas delivery nozzles 36a–36 h which extend through the reaction chamber wall 118. Preferably,each of the secondary gas delivery lines 108 a–108 d are of equal lengthand each of the tertiary gas lines 114 a–114 h are also of equal length,thereby creating a process gas distribution system wherein the processgas travels exactly the same distance before arriving at each of the gasdelivery nozzles 36 a–36 h.

As is easily appreciated from drawing FIG. 14, upon passing through eachof the active diffusers 58 a–58 d, process gas does not enter a manifoldto be distributed to each of the gas delivery nozzles 36 a–36 h.Instead, process gas passes directly from each active diffuser 58 a–58 dto an associated gas delivery nozzle 36 a–36 h through one of thetertiary gas lines 114 a–114 h. Such a design eliminates potentialcomplications associated with the use of one or more manifolds, such asinconsistent process gas pressures within the manifold orinconsistencies in the time required by the process gas exiting theactive diffusers 58 a–58 d to reach each of the gas delivery nozzles 36a–36 h.

A fifth embodiment of the gas delivery device 120 of the presentinvention is illustrated in drawing FIG. 15. The fifth embodiment of thegas delivery device 120 is similar to the fourth embodiment, in that thefifth embodiment includes a primary gas delivery line 104, a plenum 106,secondary gas delivery lines 108 a–108 c, tertiary gas lines 114 a–114f, and a plurality of gas delivery nozzles 36 a–36 f extending throughthe reaction chamber wall 118. However, the fifth embodiment differsfrom the fourth embodiment, in that the active diffusers of the fifthembodiment are divided into a first plurality of active diffusers 58a–58 c as well as a second plurality of active diffusers 124 a–124 f.Each of the secondary gas delivery lines 108 a–108 c extends between theplenum 106 and one of the first plurality of active diffusers 58 a–58 c,and each of the tertiary gas lines 114 a–114 f extends from one of thefirst plurality of active diffusers 58 a–58 c to one of the secondplurality of active diffusers 124 a–124 f. Thus, before entering thereaction chamber, process gas passes from the primary gas delivery line104, through the plenum 106, the secondary gas delivery lines 108 a–108c, the first plurality of active diffusers 58 a–58 c, the tertiary gaslines 114 a–114 f, and the second plurality of active diffusers 124a–124 f.

As is true of the previously described embodiments, the first pluralityof active diffusers 58 a-58 c, 124 a-124 f, respectively, included inthe fifth embodiment of the gas delivery device of the present inventionare placed in communication with the central controller 62 usingsuitable communication lines 57 a-57 i, such as known electrical oroptical communication lines, and each of the active diffusers 58 a-58 c,124 a-124 f, respectively, is operated under the direction of a centralcontroller 62 via the communication lines 57 a-57 i. However, becausethe fifth embodiment includes first and second pluralities of activediffusers 58 a-58 c, 124 a-124 f, respectively, the central controller62 associated with the fifth embodiment may be programmed to monitor andcontrol the first and second pluralities of active diffusers 58 a-58 c,124 a-124 f to provide various performance advantages relative to thoseembodiments already described.

For example, the first and second plurality of active diffusers 58 a-58c, 124 a-124 f, respectively, of the fifth embodiment may be controlledby the central controller 62 to provide a redundant gas delivery system.To provide a redundant gas delivery system, the central controller 62monitors and controls the first plurality of active diffusers 58 a-58 cindependently of the second plurality of active diffusers 124 a-124 f.Both the first plurality 58 a-58 c and the second plurality of activediffusers 124 a-124 f of the active diffusers are controlled by thecentral controller 62 to provide the rate of process gas flow desiredfor a particular deposition process. For example, during an initialperiod of a gas-on phase of a deposition process, the first plurality ofactive diffusers 58 a-58 c and the second plurality of active diffusers124 a-124 f may remain in a closed state. As process gas flows into thesecondary gas delivery lines 108 a-108 c and a desired minimum processgas pressure is achieved near or within each of the first plurality ofactive diffusers 58 a-58 c, the first plurality of active diffusers 58a-58 c are then controlled by the central controller 62 to provide thedesired process gas flow rate as if the process gas was passing directlyfrom the first plurality of active diffusers 58 a-58 c, through the gasdelivery nozzles 36 a-36 f and into the reaction chamber, not into thetertiary gas lines 114 a-114 f. As process gas flows from each of thefirst plurality of active diffusers 58 a-58 c and into the tertiary gaslines 114 a-114 f, the second plurality of active diffusers 124 a-124 fmay remain in a closed state until a desired process gas pressure isachieved within or near each of the second plurality of active diffusers124 a-124 f. At that time, the central controller 62 controls each ofthe second plurality of active diffusers 124 a-124 f to again providethe desired flow of process gas through each of the gas delivery nozzles36 a-36 f and into the reaction chamber. The redundancy of such a systemallows for some malfunction or error in the operation of one or more ofthe active diffusers included in the first and second pluralities ofactive diffusers 58 a-58 c, 124 a-124 f, respectively, withoutcompromising the desired process gas flow rate into the reactionchamber.

However, where the gas delivery device of the present invention does notinclude a manifold, the gas delivery system need not include tertiarygas lines. As can be seen in a sixth embodiment of the gas deliverydevice 130 of the present invention (illustrated in FIG. 16), the gasdelivery device 130 of the present invention may only include a primarygas delivery line 104, a plenum 106, secondary gas delivery lines 108a–108 h, and a plurality of active diffusers 58 a–58 h associated with aplurality of gas delivery nozzles 36 a–36 h, which extend through areaction chamber wall 118. Such a design avoids the potential problemsassociated with a gas delivery device incorporating one or moremanifolds and is simpler in construction and operation than the gasdelivery devices of the fourth and fifth embodiments.

Again, the embodiments of the gas delivery device of the presentinvention described herein are provided for illustrative purposes only.The gas delivery device of the present invention may include anydesirable number of gas delivery lines, plenums, active diffusers, gasdelivery nozzles, communication lines, pressure sensors, manifolds, etc.The design of the gas delivery device of the present invention isextremely flexible and may be easily adapted by those of ordinary skillin the art to optimize process gas delivery within any desired reactionchamber.

In each of its embodiments, however, the gas delivery device of thepresent invention provides significant advantages relative to those gasdelivery devices currently in use in CVD deposition processes. First,due to the plurality of centrally-controlled active diffusersincorporated into each of the various embodiments, the gas deliverydevice of the present invention provides precise control of process gasflow within any given reaction chamber, even where inconsistent processgas pressures are experienced throughout the deposition process.Moreover, the gas delivery device alleviates or completely eliminatesproblems resulting from inconsistencies in the time required by processgas to reach and flow through the various gas delivery nozzles extendinginto a reaction chamber. Thus, the gas delivery device of the presentinvention provides the control necessary to enable reliable depositionof high-quality material layers within state of the art semiconductordevice features having high-aspect ratios and opening widths measuringmuch less than 0.5 Φm.

In addition, the gas delivery devices of the present invention enablethe detection of line blockages or other malfunctions that occasionallyoccur within a gas delivery system. For example, the inside diameter ofthe gas delivery nozzles currently used to deliver process gas inreaction chambers is exceedingly small, and the nozzles are easilyblocked, either partially or completely, by small contaminants that maybe present in the process gas, or, alternatively, gas lines leading tothe gas delivery nozzles may also be progressively fouled orunexpectedly blocked. Such blockages or fouling often result in backpressures, and, particularly where no manifold is included in the gasdelivery device of the present invention, such back pressures willinhibit process gas from flowing through the active diffusers asexpected. As process gas is inhibited from flowing from the activediffusers, the process gas pressure in the gas line preceding the activediffuser will unexpectedly build. Such an unexpected increase inpressure would be sensed by the pressure sensor incorporated in orlocated near the active diffuser, and the central controller may beprogrammed to detect such unexpected pressure changes so that any damageto the system or to the semiconductor materials being processed may beavoided or minimized. Further, the central controller associated witheach embodiment of the gas delivery device of the present invention mayalso be programmed to detect significant decreases in process gaspressure that may occur due to a rupture, fouling, or a blockage thatoccurs in a gas line preceding an active diffuser.

Also included within the scope of the present invention is a CVDchamber, a cross section of which is schematically illustrated indrawing FIG. 17. The CVD chamber 148 according to the present inventionincludes a sealable chamber 150 that may be used to enclose one or moresemiconductor wafers 152. Such sealable chambers are well known in theart. Moreover, the CVD chamber 148 of the present invention may alsoinclude various other known features necessary to carry out anydesirable CVD process, such as an RF source, a heating apparatus, one ormore ventilation systems, or substrate handling equipment, all of whichare well known in the art. However, unlike known CVD chambers, the CVDchamber 148 of the present invention also includes a gas delivery device154 of the present invention. Though the CVD chamber 148 illustrated indrawing FIG. 17 incorporates a gas delivery device 154 according to thesixth embodiment (FIG. 16) of the gas delivery device of the presentinvention, the CVD chamber 148 of the present invention may incorporateany embodiment of the gas delivery device of the present invention.

The present invention also includes a method of carrying out a CVDprocess. The method of the present invention includes providing a CVDchamber, providing a gas delivery device according to any one of theembodiments of the gas delivery device of the present invention,disposing a semiconductor substrate within the HDP CVD chamber, andintroducing any suitable process gas, such as SiH₄, an inert gas, anoxygen-containing gas, or a nitrogen containing gas, into the CVDchamber using the gas delivery device of the present invention. Themethod of the present invention is extremely flexible and is easilyadapted for use in any desired CVD process, such as TE CVD, PE CVD, orHDP CVD processes.

Again, although various embodiments of the gas delivery device, thereaction chamber and the method of carrying out a CVD process of thepresent invention are described and illustrated herein, the presentinvention is not so limited. As is easily appreciated by the descriptionprovided herein, the gas delivery device, the reaction chamber, and themethod of carrying out a CVD process of the present invention are eachhighly flexible, and the various embodiments described herein may beeasily modified in harmony with the present invention in order to suit aparticular process need. Therefore, the gas delivery device, thereaction chamber, and the method of carrying out a CVD process of thepresent invention may be designed for use in any desirable CVD process,such as TE CVD, PE CVD, or HDP CVD processes, and the scope of thesevarious aspects of the present invention is defined by the appendedclaims.

1. A method for depositing a material over a semiconductor substrate,comprising: using a reaction chamber; using a gas delivery devicecomprising a gas delivery system, a plurality of gas delivery nozzlesextending into the reaction chamber, and a plurality of activediffusers, each active diffuser of the plurality of active diffusersbeing independently controllable from each other by a central controllerto provide a desired amount of process gas flow from the gas deliverysystem, through the plurality of gas delivery nozzles, and into thereaction chamber; placing the semiconductor substrate within thereaction chamber; and introducing process gas within the reactionchamber via the gas delivery device.
 2. A method for depositing amaterial over a semiconductor substrate in a reaction chamber,comprising: connecting a gas delivery device to the reaction chamber,the gas delivery device comprising a gas delivery system, a plurality ofgas delivery nozzles extending into the reaction chamber, and aplurality of active diffusers, each active diffuser of the plurality ofactive diffusers being independently controllable from another activediffuser by a central controller to provide a desired amount of processgas flow from the gas delivery system, through the plurality of gasdelivery and the reaction chamber; placing the semiconductor substratewithin the reaction chamber; and introducing process gas within thereaction chamber via the gas delivery device.
 3. A method for asemiconductor substrate using a reaction chamber, comprising: connectinga gas delivery device to the reaction chamber, the gas delivery devicecomprising a gas delivery system, a plurality of gas delivery nozzlesextending into the reaction chamber, and a plurality of activediffusers, each active diffuser of the plurality of active diffusersbeing independently controllable from another active diffuser by acentral controller to provide a desired amount of process gas flow fromthe gas delivery system, through the plurality of gas delivery nozzles,and into the reaction chamber; placing the semiconductor substratewithin the reaction chamber; and introducing process gas within thereaction chamber via the gas delivery device.
 4. A method for asemiconductor substrate comprising: connecting a gas delivery device toa reaction chamber, the gas delivery device comprising a gas deliverysystem, a plurality of gas delivery nozzles extending into the reactionchamber, and a plurality of active diffusers, each active diffuser ofthe plurality of active diffusers being independently controllable fromanother active diffuser connected to the gas delivery system by acentral controller to provide a desired amount of process gas flow fromthe gas delivery system, through the plurality of gas delivery nozzles,and into the reaction chamber; placing the semiconductor substratewithin the reaction chamber; and introducing process gas within thereaction chamber via the gas delivery device.
 5. A process for asemiconductor substrate comprising: connecting a gas delivery device toa reaction chamber, the gas delivery device comprising a gas deliverysystem, a plurality of gas delivery nozzles extending into the reactionchamber, and a plurality of active diffusers, each active diffuser ofthe plurality of active diffusers being independently controllable fromanother active diffuser in the gas delivery system by a centralcontroller to provide a desired amount of process gas flow from the gasdelivery system, through the plurality of gas delivery nozzles, and intothe reaction chamber; placing the semiconductor substrate within thereaction chamber; and introducing process gas within the reactionchamber via the gas delivery device.
 6. A process for a substratecomprising: connecting a gas delivery device to a reaction chamber, thegas delivery device comprising a gas delivery system, a plurality of gasdelivery nozzles extending into the reaction chamber, and a plurality ofactive diffusers, each active diffuser of the plurality of activediffusers being independently controllable from any diffuser in the gasdelivery system by a central controller to provide a desired amount ofprocess gas flow from the gas delivery system, through the plurality ofgas delivery nozzles, and into the reaction chamber; placing thesubstrate within the reaction chamber; and introducing process gaswithin the reaction chamber via the gas delivery device.